The invention relates to an apparatus for making electrical contact with luminous means in spotlights.
DE 198 16 364 C2 has disclosed a lamp housing, which is used for accommodating a luminous body, a transparent cover plate in the form of a protective plate or a lens plate and a reflector. Burners or lamps, preferably diskharge lamps with a base at one end, with a vertical or horizontal installed position, i.e. in each case at right angles to the optical axis, or with an axial installed position, i.e. in the optical axis, are used as luminous means or luminous bodies.
The lamps have a gas-filled glass body with electrodes arranged therein, a lamp base, through which the feed lines to the electrodes are passed, and two or more contact pins, which are arranged on that end of the lamp base which is opposite the glass body. The contact pins are inserted into the sockets of a lampholder connected to the lamp housing in order to connect the lamp to a voltage source, a tight fit between the sockets and the contact pins being necessary for the high current levels of the lamp current to be transmitted.
At the same time, the contact pins, for example of diskharge lamps with a base at one end, are used as fastening means for the diskharge lamp. Since, as lamp powers increase, also the physical size of the diskharge lamps and in particular the physical, length of the glass body and of the lamp base increase, the lamps in the case of relatively high lamp powers have such a physical size that, in particular in the case of a horizontal installed position of the diskharge lamps, considerable forces are exerted on the contact pins which, in addition to the power supply, also act as fastening contacts.
These forces result in an impairment of the contact between the contact pins and the sockets of the lampholder, which is associated with increased transfer resistance when transmitting the lamp current, a displacement of the lamp from the focal point of the reflector and, as a result of this, a reduced luminous efficiency and with a transmission of the forces into the lamp interior, which may result in impermissible voltages and ultimately in failure of the lamp.
The disadvantages of mounting the lamp exclusively via the contact pins are not only noticeable in the steady-state range over the physical size of the lamp, however, but in particular also in the dynamic range during transport of a spotlight or its operation with jerky pivoting movements, impacts on the lamp housing and the like.
In order to be able to use a lamp housing for lamps with different lamp base diameters without replacing an accommodating device and to be able to use the contact pins of the lamps exclusively for transmitting the lamp current, in the case of the lamp housing known from DE 198 16 364 C2 the accommodating device comprises clamping jaws, which engage around the lamp base and can be adjusted by means of the adjusting device into an opening position, in which the lamp base is released, and into a locking position, in which the lamp base is fixed. The adjusting device comprises a latch with two sloping faces, which are designed to be identical geometrically and bear against the upper and lower clamping jaw in such a way that, when the latch is adjusted, the clamping jaws are spread apart radially.
When the adjusting device is actuated for the purpose of opening and closing the clamping jaws, at the same time an opening and closing of the sockets accommodating the contact pins of the luminous means takes place, so that, as a result of the contact pins being released at the same time, when the adjusting device is actuated for opening and closing the clamping jaws the luminous means can be removed easily as a result of the luminous means base being released or a luminous means can be inserted in the opening position of the lampbracket.
Generally, the lampholders or luminous means holders, depending on the power level of the spotlight, are designed for accommodating a luminous means corresponding to this power level, i.e. a lamp or a burner having a predetermined power consumption and/or power output. If a luminous means having a different power level is intended to be used in order to make use of the spotlight housing in a way which is largely independent of the power, this fails because of the different distances between and diameters of the contact pins of the luminous means, which generally increase as the power of the luminous means increases as a result of the different current consumption of luminous means having different power levels and for reasons of the mechanical construction of the luminous means. When using a spotlight housing, this makes it necessary to replace not only the luminous means holder but also the entire lamp mount, which accommodates and is connected to the luminous means holder, although the lamp mount is capable of accommodating lamps or burners with different dimensions, in particular the luminous means base.